In a new study this week, doctors describe a form of self-injury among teenagers called self-embedding, which involves inserting objects into the skin or muscle.
The researchers say embedding is on the spectrum of self-harming behaviors, but a much more severe form that appears to be linked to thoughts of suicide and major psychiatric disorders.
"There's clearly a more severe intent to hurt themselves than cutting," said Dr. William Shiels, a radiologist at Nationwide Children's Hospital in Columbus, Ohio and one of the authors of the study.
"Inserting a 16 cm paperclip - not just to do that on one arm, but both arms - the intent that's required to cause that much self harm is significant," he said.
Self-injury, which is often in the form or cutting or burning, is a fairly common behavior, with estimates ranging between 4 and 30 percent of youth who have hurt themselves in some way.
The pain involved in self-harm is thought to provide a sense of psychological relief, and is generally not considered part of a suicide attempt.
Self-embedding is a rare behavior that few doctors have noted, Shiels said.
He and his colleagues had noticed that several patients at his hospital required objects to be removed from their bodies - objects that were intentionally put there.
To see if there were other cases like these, they looked through 600 medical records of children who had material removed from their tissue, and found 21 instances of intentional embedding among 11 patients between the years 2005 and 2008.
All the patients were teenagers - most of them girls -- between 14 and 18 years old, and had come to the hospital because they had admitted embedding an object or because they ended up with an infection at the site.
Staples, pencil lead, and paperclips were the most common objects, often inserted into the arm.
One teenager was treated four times for a total of 35 objects - including a crayon and a nail polish wand - stuck into the arm. Another patient pushed a piece of glass into her neck.
All the patients had bipolar disorder, which is a mood disorder marked by cycles of mania and depression. Most of the teens suffered additionally from post-traumatic stress disorder, and others also had depression, borderline personality disorder, or attention deficit-hyperactivity disorder.
Ten of the patients lived in a group psychiatric home, though not the same one.
Shiels told Reuters Health that the multiplicity of disorders among these teens is one of the differences between embedding and other forms of self-injury.
"With self-embedding behavior we see more severe behavioral health abnormalities," Shiels said.
The study, which is published in the journal Pediatrics, also found that 90 percent of those who self-embedded had thoughts of suicide.
Nancy Heath, a professor at McGill University, said that self-injury among children is usually tied to a sense of relief or feeling better, "whereas self-embedding behavior does not appear to have that. It's much more about self harm."
Shiels could not estimate how common self-embedding is.
He said he'd like to set up a national registry to get a better handle on how many people self-embed.
"I think it is definitely a phenomenon that is out there that exists," said Heath, who was not involved in this study.
Because of the severity of the behavior, the approach to treating teens who self-embed should be slightly different than to those who cut or burn themselves, Heath told Reuters health.
Anyone who harms herself should get an evaluation for suicide risk, but self-embedding warrants more intense interventions.
"With the self-embedding behavior, until we have any evidence to the contrary, at this point one would be extra cautious...and one would suggest a full psychiatric consultation," Heath said.